MATHEMATICAL-MODELING OF IMMOBILIZED ANIMAL-CELL GROWTH

A two-dimensional mathematical model for animal cell growth was employ ed to study the suspension, as well as stationary, culture of microenc apsulated and gel immobilized animal cells. For stationary microcapsul es with low-viscosity intracapsular liquid, it was found that capsule radius, capsule loading and medium-change time have the most significa nt effects on the intracapsular cell density. The model was also adapt ed to simulate other scenarios of cell growth such as in gel beads and suspended microcapsules. The simulated time course of oxygen concentr ation and specific growth rate revealed a complicated interaction betw een material transport and cell growth kinetics. With the mass transfe r coefficient for oxygen transfer (K(L)a') into the medium equal to 4. 0 hr(-1), for instance, it was found that the specific growth rate of the microencapsulated cells was controlled by the supply of glucose an d oxygen. When the value of K(L)a' was reduced to 0.6 hr(-1), however, oxygen supply appeared to be the sole factor affecting the specific g rowth rate. In the case of suspended gel beads, a simulation revealed a higher cell density towards the gel bead surface. The transport of n utrients and oxygen to the central region of the gel bead was apparent ly blocked by the surrounding cells.